This invention relates to novel tricyclic fused pyrimidine derivatives useful as medicines.
Patent applications directed to pyrazolo[3,4-d]pyrimidine derivatives having, among others, analgesic, antiinflammatory and diuretic actions [cf. Japanese Unexamined Patent Publication No. 53-31694, Japanese Unexamined Patent Publication No. 61-5082 which corresponds to European Patent Publication No. 0166054, etc.] have been made, but the instant tricyclic fused pyrimidine derivatives are novel compounds whose heterocyclic skeleton itself is not known up to now.
The present invention provides tricyclic fused pyrimidine derivatives having analgesic, antiinflammatory, anti-allergic, anti-psoriatic and liver-protecting activities and having a novel skeleton.